*According to tradition, three Muslim zealots (purists later termed Kharijites) had agreed to assassinate Ali, Mu'awiyah and `Amr. The assassins sent against Mu'awiyah and `Amr failed; the only assassin who succeeded was the one who attacked Ali. Ali suffered a mortal head wound on the 19th of Ramadan while he was performing morning prayers in mosque in the city of Kufa. Some say that the sword that wounded him was poisoned. According to the Shia tradition, as he was being struck, Ali said "By the Lord of the Ka'bah, I have succeeded"!***Wikipedia